:: COMPARE ::
The short answer
They sound like the same idea and aren't. Object permanence is Piaget's: a hidden ball still exists — first signs around eight to twelve months, full understanding nearer two years, and no settled scientific consensus on the timing. Object constancy is Mahler's: a person you're furious with is still the person you love, which takes years and, for some people, never fully settles.
Side by side
| Aspect | Object constancy | Object permanence |
|---|---|---|
| Theorist | Mahler | Piaget |
| About | People | Things |
| Domain | Emotional | Cognitive |
| Arrives | Years | ~8–24 months |
What each one means
In psychoanalysis, the capacity to keep a stable, whole picture of someone — and stay connected to your good feelings about them — when they're absent, disappointing, or you're angry with them. In perceptual psychology the same phrase means something else entirely: seeing an object's size, shape and colour as constant even as distance, angle and light change.
Full definition of Object Constancy →The contrast above sets out how Object permanence differs from Object Constancy on the points that actually matter.